Brief Summary

The genus Hippocampus is made up of 47 species of distinctive marine fish commonly known as the seahorses. They are found world-wide in protected, shallow tropical and temperate waters, especially estuaries, mangrove swamps, coral reefs, and eel grass beds. Seahorses do not have scales, instead have bony plates for protection, and swim slowly in an upright posture. They spend much of their time stationary, using their tails to attach themselves to corals, grasses, or other objects. They are ambush predators and feed on small crustaceans and other invertebrates.

Fossil and molecular dating evidence indicate that sea horses diverged from their closest relatives, the pipefish, in the Oligocene, about 13 million years ago.

Sea horses are well-known for their paternal care. After several days of courting, the female seahorse oviposits somewhere between a dozen and a thousand eggs into the male’s egg pouch, which is located on his pouch. The male regulates the water salinity in the pouch and incubates the eggs for 1-6 weeks, depending on the species. After the fry (typically 100-200, but this varies by species) emerge, he no longer provides any more care. Sea horses often form monogamous pairs for the breeding season, but many species trade partners readily and do not pair for life.

Sea horses are found in the aquarium trade, however they are difficult to keep. They can be bred in captivity, but tend to be cheaper when harvested from the wild. Sea horses are collected and used as aphrodisiacs and cures for respiratory ailments in traditional Chinese medicinal purposes; between collecting and destruction of environments, some are thought to be declining in numbers. CITES set up a set of trade recommendations with guidelines for international trade of all sea horse species in 2004.

A basal seahorse clade, now comprised of six species, contains the pygmy seahorses, which are less than 15 mm tall. Because of their small size, camouflage and commensurate living habits with colonial hydrozoans and coralline algae these species have been noticed and classified only since 1997.